There is no requirement to write any sponsorship letters for an EEA Family Permit application.
So, your husband does not need to write one at all.
You can include a contents letter if you like, where you can explain your refused entries. No need to include any other letters.
For example:
To the Entry Clearance Officer,
Please find enclosed my application and supporting documents for an EEA Family Permit to join my EU citizen husband in the UK. I would like my permit to start on X date.
I have two previous refused entries to the UK and I am including paperwork from them (if applicable). I was refused entry on ____ because ____ and on ____ because _____.
The supporting documents included with this application are as follows:
-
-
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Yours Sincerely,
Your Name
So, in short:
- no letter from your husband
- simple contents letter from you addressing the refused entries